Funding is requested for a set of upgrades to the fluorescence activated cell sorter (FACS) in the Institutional Flow Cytometry Laboratory at the University of Texas Health Science Center at San Antonio. The present instrument in this laboratory is a Becton-Dickinson FACStar Plus purchased in 1985 with an NCRR Shared Instrumentation Grant. This instrument has supported a productive and diverse group of NIH-funded investigators; the major user of group of 11 investigators holds 1.9 million dollars per annum in NIH funding accounting for 83 percent of instrument utilization. However, the instrument now is in need of major upgrading to meet the continuing needs of these investigators. The upgrades requested include: (1) addition of turbosorting-permitting sort rates up to 10,000 events per second with 99 percent purity (presently maximal sort rates are 2000 events per second with approximately 95 percent purity); (2) addition of a third laser with both uv-and 488-nm capabilities (presently the instrument lacks a uv-laser and both present lasers have logged greater than 5,000 hours of use); (3) a computer work station to provide for simultaneous analysis of previously stored data while samples for FACS analysis or sorting are being run (not now possible in the facility); and (4) new cell sorting and analytical software (current software is first generation and significantly outdated in terms of precision, flexibility, and efficiency). The FACS facility has been a fundamental core resource at UTHSCSA for 14 years. The requested upgrades will permit this facility to continue to provide availability of state-of-the-art flow cytometric analysis and sorting to the UTHSCSA community.